Some gas turbine engines utilize variable stator vanes that are actuated about their rotational axes to improve overall compressor characteristics. A synchronizing assembly is used to accurately control the position of the vanes. One type of synchronizing assembly includes a synchronizing ring that is controlled relative to a compressor case by actuators. Multiple bumpers are circumferentially arranged between the synchronizing ring and a compressor case to facilitate movement of the synchronizing ring throughout the changing clearances.
In one example, shimmed bumpers or runners are used to center the synchronizing ring and provide a wear surface to pads on the compressor case. The bumpers should provide a low friction, wear resistant structure that is inexpensive to manufacture and install.